Personal Health

By Jane E. Brody

Published: November 18, 1992

Correction Appended

BEVERLY MIELKE was a middle-class 3-year-old who in 1984 lived in a well-kept home in St. Paul. So what was she doing with lead poisoning? The problem was eventually traced to a lead-contaminated sandbox at her day-care center.

Her father, a toxicologist, was appalled at how easily his daughter had accumulated dangerous levels of lead in her blood, levels that recent studies have shown can permanently damage a young child's brain.

As Beverly's case shows, a child does not have to be poor or live in dilapidated housing to suffer permanent intellectual impairment from low-level lead poisoning. Lead is a widespread environmental pollutant, and new studies show that it is an insidious poison that can damage affluent white children just as easily as it can harm the poor black children who are its most frequent victims in this country.

The new studies support the concern of Federal health officials who describe lead poisoning as the No. 1 environmental problem facing American children. The findings counter assertions from the lead industry that genetic and socioeconomic factors are mainly responsible for the lowered intelligence that has been linked to lead.

Studies following children from before birth show that exposure to levels of lead that were long considered safe can lower intelligence and that the effects are noted in middle-class and affluent white children as well as in poor black and Hispanic children. Other studies suggest similar low lead levels cause behavioral abnormalities in young children, particularly undue aggressiveness.

The studies also show that lead damage to the brain can start even before birth if the pregnant woman has elevated levels of lead in her body.

The findings show that even though efforts to reduce lead exposure have drastically cut cases of obvious lead poisoning in young children, current exposure limits are not low enough to prevent brain damage in millions of American children. Many of the children studied had measurable, lasting losses in intelligence associated with levels of lead that produce no apparent physical symptoms and that are not currently considered a cause for aggressive action. Sources of Lead

Lead is everywhere: in air, water, soil, food, dust. It gets into the air from industrial and vehicular emissions, from tobacco smoke and paint dust and from the burning of solid wastes that contain lead. Airborne lead levels dropped sharply after the nation began phasing out leaded gasoline, but many vehicles still use fuel containing lead.

Lead occurs naturally in soil, which also collects lead from the air and other sources. When crops are grown in soil containing lead, the poison can enter the food chain. Other sources of lead include foods stored or served in lead-glazed pottery or lead crystal as well as processed foods sold in lead-soldered cans. Despite a Federal ban on using these cans for food, many imported foods are still sold in lead-soldered cans.

Lead is also a natural constituent of surface and ground waters that supply drinking water to many millions of Americans. The use of lead in plumbing is now banned, but it can still get into drinking water from old water pipes that contain lead.

House dust is a common source of lead for young children, who pick up the dust on their hands and then put their hands in their mouths. The dust can become contaminated with lead from the air and from flaking house paint that contains lead. The use of indoor paints containing lead was banned in 1977, but about 57 million homes built before then contain leaded paints. Conventional methods for removing paint, like sanding or scraping, can fill the air with lead.

Young children absorb far more lead than adults exposed to the same levels, and absorption is highest among those with iron deficiency, a problem especially prevalent among poor children. Children in inner cities are especially vulnerable because they often live in old homes with flaking lead-based paint and in areas where lead contamination from industry and vehicles is high. Dangerous Levels

Lead was once considered a hazard only if blood levels were high enough to produce obvious physical symptoms. But more recently it has been shown to wreak havoc with the developing nervous system at very low levels that cause no outward symptoms of poisoning. This prompted a redefinition of lead poisoning in children as 25 or more micrograms of lead per 10 deciliters of blood.

Then came evidence that even this was not low enough. Millions of children were, and still are, suffering adverse brain effects from levels of lead in the blood that are considerably below 25 micrograms. So a year ago the Federal Centers for Disease Control and Prevention in Atlanta lowered the level of lead at which children are considered poisoned to 10 micrograms per deciliter, an amount that can be found in three million children under 6, or 10 to 15 percent of the nation's preschoolers.

According to a carefully designed Australian study published in October in The New England Journal of Medicine, as blood lead levels in infancy rise to 35 from 10 micrograms, middle-class white children suffer an average drop of 5 percent in I.Q. scores by the age of 10. Another unpublished study among affluent children in the Boston area is showing similar effects from lead levels that average below 10 micrograms.

From such findings, public health experts have concluded that there is no such thing as a "safe" level of lead in young children. Any amount can injure the developing nervous system, and children who are already of low-normal intelligence can become educational failures as a result of exposure to low levels of lead. Avoiding Lead

Pregnant women and families with infants and preschoolers would be wise to take precautions against lead exposure. In a report last June, Congressional Quarterly Researcher made these recommendations:

If you live in a house built before 1950, let the paint alone if it is good condition or has been painted over with lead-free paint. Paint removal should be done by a contractor certified to do lead-abatement work, pregnant women and small children should live elsewhere during renovation, and all dust should be cleaned up afterward with an industrial vacuum.

Drinking water can be tested for lead for about $50 by laboratories certified by the Environmental Protection Agency. Avoid softening your drinking water, since soft water can leach lead from pipes. Use only cold water for drinking and cooking and let it flow for a minute or two first.

Avoid imported canned foods. Unless you are sure that the glaze is free of lead, avoid cooking in ceramicware and do not routinely use ceramic dishes or old china with a damaged glaze to serve hot or acidic foods, including coffee and tea. Do not store acidic juices in ceramic pitchers, and do not use lead crystal decanters for storing any drinks.

Diagram: "Sources of Lead" Because they live a hand-to-mouth existence, children can easily ingest lead dust form their environment. (Source: Consumers Union Foundation)

Correction: November 28, 1992, SaturdayDecember 10, 1992, Thursday The Personal Health column on Nov. 18 about lead poisoning in children referred incorrectly to Beverly Mielke. Although she was exposed to lead in 1984, when she was 3 years old, she suffered no permanent damage. Her exposure was discovered early and the source of the lead, a sandbox, was decontaminated. The Personal Health column on Nov. 18 about lead poisoning misstated a level at which children were formerly considered to be poisoned. It was 25 or more micrograms of lead per deciliter of blood. As the article stated, the level at which children are now considered poisoned is 10 micrograms per deciliter.